A cantilever is a projecting structure that is supported at only one end. Macroscopic cantilevers have been used to monitor surface stresses for over 30 years. For instance, several groups have utilized macroscale cantilevers to monitor stress development in ultraviolet-cured polymer coatings [Wen, M., L. E. Scriven, and A. V. McCormick. Differential scanning calorimetry and cantilever deflection studies of polymerization kinetics and stress in ultraviolet curing of multifunctional (meth)acrylate coatings. Macromolecules, 35, 112-120 (2002); Payne, J. A., L. F. Francis, and A. V. McCormick. The effects of processing variables on stress development in ultraviolet-cured coatings. J. Appl. Polym. Sci., 66, 1267-1277 (1997); Lange, J., S. Toll, J. E. Manson, and A. Hult. Residual stress build-up in thermoset films cured above their ultimate glass transition temperature. Polymer, 36, 3135-3141 (1995)]. In these applications, the surface stress differences measured are on the order of a few mPa. Microcantilevers are used for measurement of deflections resulting from small surface stress changes or surface mass changes due to adsorption of molecules.
Since the invention of the atomic force microscope (AFM), microcantilevers have been utilized as ultra-sensitive force sensors in AFM systems. In the early 1990's, researchers demonstrated that they were able to measure molecular forces, such as avidin-biotin binding [Florin, E. L., V. T. Moy, and H. E. Gaub. Adhesion forces between individual ligand-receptor pairs. Science, 264, 415-417 (1994)], antigen-antibody interaction [Hinterdorfer, P., W. Baumgartner, H. J. Gruber, K. Schilcher, and H. Schindler. Detection and localization of individual antibody-antigen recognition events by atomic force microscopy. Proc. Natl. Acad. Sci. U.S.A., 93, 3477-3481 (1996)], and hybridization of complementary DNA strands interactions [Lee, G. U., L. A. Chrisey, and R. J. Colton. Direct measurement of the forces between complementary strands of DNA. Science, 266, 771-773 (1994)] using AFM systems. These remarkable accomplishments resulted in many groups focusing research on developing microsensors based on the silicon microcantilevers that are responsible for this tremendous sensitivity.